Best Vitamins to Take on Semaglutide 2026: Complete Supplement Guide
What vitamins and supplements should you take while on semaglutide (Wegovy/Ozempic)? Learn which nutrients prevent deficiencies, support healthy weight loss, and help minimize common side effects.
Medical Disclaimer
This article is for educational purposes only and is not medical advice. Always consult your healthcare provider before starting any new supplements, especially while taking prescription medications. Individual nutritional needs vary based on diet, health conditions, and other factors.
Quick Answer
Most people on semaglutide should take a high-quality multivitamin plus additional vitamin B12, vitamin D, and protein supplementation. Because semaglutide dramatically reduces appetite and food intake, you're likely eating 30-50% fewer calories—which means significantly fewer vitamins and minerals from food.
The most common deficiencies on semaglutide are: vitamin B12, vitamin D, calcium, magnesium, iron (especially in women), and inadequate protein intake.
Supplementation isn't optional—it's essential for maintaining muscle mass, energy levels, bone health, and preventing long-term nutritional deficiencies during treatment.
Why Vitamin Supplementation Is Critical on Semaglutide
Semaglutide is extremely effective at suppressing appetite and reducing caloric intake—but this creates a nutritional challenge:
1. Dramatically Reduced Calorie and Nutrient Intake
Most semaglutide users reduce their daily calorie intake by 500-1,500 calories. When you eat significantly less food, you consume proportionally fewer vitamins and minerals—even if you're making healthy food choices.
Example: If you previously ate 2,000 calories daily and now eat 1,200 calories, you're getting 40% fewer vitamins and minerals from food—even if your diet quality hasn't changed.
2. Food Aversions and Changed Preferences
Many semaglutide users develop strong aversions to previously enjoyed foods—particularly meat, which is a primary source of protein, iron, and B vitamins. If you can't tolerate nutrient-dense foods, deficiencies develop quickly.
3. Potential Nutrient Absorption Issues
Delayed gastric emptying may affect how efficiently you absorb certain nutrients, particularly those that require stomach acid for optimal absorption (like vitamin B12, iron, calcium, and magnesium).
4. Risk of Muscle Loss During Rapid Weight Loss
Studies show that 25-40% of weight lost on GLP-1 medications can be lean muscle mass—not just fat—if protein intake is inadequate. Maintaining muscle requires sufficient protein, vitamin D, calcium, and magnesium.
Why this matters: Losing muscle slows your metabolism, reduces strength and mobility, and can lead to long-term health problems. Proper supplementation helps preserve muscle during weight loss.
Bottom line: Vitamin and mineral supplementation isn't a nice-to-have on semaglutide—it's essential for preventing deficiencies, maintaining muscle mass, supporting energy levels, and ensuring healthy weight loss.
Essential Vitamins & Supplements: Ranked by Priority
1. High-Quality Multivitamin
Recommended Dosage:
One high-quality multivitamin daily. Choose formulas designed for adults or those labeled "once daily" or "complete."
Why It's Essential:
- ✓Covers baseline needs: Provides a safety net for vitamins and minerals you're not getting from reduced food intake
- ✓Prevents common deficiencies: Addresses vitamins A, C, E, K, and trace minerals often lacking on restricted diets
- ✓Supports immune function: Adequate vitamins and minerals help maintain immune health during weight loss
- ✓Easy and convenient: One pill covers multiple nutritional gaps
What to Look For:
- • Contains 100% Daily Value (DV) for most vitamins and minerals
- • Includes methylated B vitamins (methylcobalamin B12, methylfolate) for better absorption
- • Third-party tested (USP, NSF, or ConsumerLab verified)
- • Avoid "mega-dose" formulas with excessive amounts (200-500%+ DV)
Best brands: Thorne, Pure Encapsulations, Garden of Life, Nature Made (USP verified), Ritual, or similar high-quality brands. Avoid cheap drugstore multivitamins with poor absorption rates.
2. Vitamin B12 (Methylcobalamin or Cyanocobalamin)
Recommended Dosage:
500-1,000 mcg daily (in addition to multivitamin). Sublingual (under the tongue) or oral tablets both work.
Why It's Critical:
- ✓Most common deficiency: B12 deficiency is extremely common on semaglutide due to reduced meat/animal product intake
- ✓Energy and mood: B12 is essential for energy production, brain function, and mood regulation
- ✓Prevents anemia: Low B12 causes fatigue, weakness, and megaloblastic anemia
- ✓Absorption issues: Delayed gastric emptying may reduce B12 absorption from food
Signs of B12 Deficiency:
- • Extreme fatigue and weakness
- • Brain fog, difficulty concentrating
- • Mood changes, depression, irritability
- • Tingling or numbness in hands/feet
- • Pale skin, shortness of breath
Important: If you're experiencing severe fatigue on semaglutide, ask your doctor to check your B12 levels. Deficiency is easily treatable but can cause serious neurological damage if left untreated.
3. Vitamin D3 (with Vitamin K2)
Recommended Dosage:
2,000-4,000 IU vitamin D3 daily, ideally paired with 100-200 mcg vitamin K2 (MK-7). Take with a meal containing fat for better absorption.
Why It's Essential:
- ✓Muscle preservation: Vitamin D is critical for maintaining muscle mass during weight loss
- ✓Bone health: Prevents bone density loss during rapid weight loss
- ✓Immune support: Adequate D3 levels support immune function
- ✓Mood regulation: Low vitamin D is linked to depression and low energy
- ✓K2 synergy: Vitamin K2 ensures calcium goes to bones (not arteries)
Pro tip: Ask your doctor to test your vitamin D levels (25-hydroxyvitamin D test). Optimal levels are 40-60 ng/mL. Many people are deficient even before starting semaglutide.
4. Protein Powder or Protein Supplementation
Recommended Intake:
0.7-1.0 grams of protein per pound of ideal body weight daily. For most people, this means 80-120g protein per day—difficult to achieve on reduced food intake.
Why It's Essential:
- ✓Prevents muscle loss: Adequate protein is THE most important factor in preserving lean muscle during weight loss
- ✓Maintains metabolism: Muscle tissue burns more calories at rest than fat tissue
- ✓Supports satiety: Protein keeps you fuller longer
- ✓Easier to consume: Protein shakes are easier to tolerate than solid food when appetite is suppressed
Best Options:
- • Whey protein isolate (20-30g per serving, fast-absorbing)
- • Plant-based protein (pea, rice, hemp blend for vegans)
- • Collagen peptides (10-20g, supports skin elasticity during weight loss)
- • Bone broth protein (easy on sensitive stomachs)
Critical: Prioritize protein at every meal. Aim for 25-30g protein per meal. If you can't eat enough solid food, protein shakes are essential—not optional—on semaglutide.
5. Calcium + Magnesium
Recommended Dosage:
500-1,000 mg calcium citrate + 300-400 mg magnesium glycinate or citrate daily (split into two doses for better absorption).
Why It's Important:
- ✓Bone density: Rapid weight loss can cause bone mineral loss if calcium intake is inadequate
- ✓Muscle function: Both minerals are essential for muscle contraction and recovery
- ✓Reduced dairy intake: If you're eating less dairy, calcium supplementation becomes necessary
- ✓Magnesium for constipation: Can help with common semaglutide side effect
Note: Calcium and magnesium work together. Don't supplement one without the other. Take calcium citrate (not carbonate) for better absorption, especially with delayed gastric emptying.
6. Iron (If Deficient or at Risk)
Recommended Dosage:
18-27 mg daily (premenopausal women) or 8 mg daily (men/postmenopausal women). Only supplement if you're deficient or at high risk.
Who Needs It:
- ✓Premenopausal women (especially with heavy periods)
- ✓People with documented iron deficiency or anemia
- ✓Vegetarians/vegans on semaglutide
- ✓Anyone who has developed a meat aversion on the medication
Signs of Iron Deficiency:
- • Extreme fatigue and weakness
- • Pale skin, nail beds
- • Shortness of breath during normal activities
- • Cold hands and feet
- • Brittle nails, hair loss
Important: Don't supplement iron unless you need it—excess iron can cause constipation and other issues. Get your iron levels tested (ferritin, CBC) before starting supplementation.
7. Omega-3 Fatty Acids (Fish Oil or Algae Oil)
Recommended Dosage:
1,000-2,000 mg combined EPA/DHA daily. Choose high-quality fish oil or algae-based omega-3s.
Why It's Beneficial:
- ✓Heart health: Supports cardiovascular health during weight loss
- ✓Anti-inflammatory: Reduces inflammation associated with obesity
- ✓Brain health: Supports cognitive function and mood
- ✓Reduced fish intake: If you're eating less fatty fish, supplementation helps maintain omega-3 levels
8. Electrolyte Supplementation (Optional)
Sugar-free electrolyte drinks (LMNT, Ultima, Nuun) can help with hydration, reduce nausea, and prevent electrolyte imbalances—especially if you're experiencing vomiting or diarrhea.
How to Take Your Supplements on Semaglutide
1. Take Fat-Soluble Vitamins With Food
Vitamins A, D, E, and K require dietary fat for absorption. Take your multivitamin and vitamin D with a meal containing fat (eggs, avocado, nuts, olive oil). Even a small amount of fat (5-10g) improves absorption significantly.
2. Split Calcium and Iron Doses
Calcium and iron compete for absorption. If you take both, take them at different times (calcium in the morning, iron in the evening, or vice versa). Your body can only absorb about 500 mg of calcium at once, so split larger doses.
3. Take B12 Sublingually for Best Absorption
Sublingual B12 (under the tongue) bypasses the stomach and absorbs directly through the mucous membranes. This may be more effective on semaglutide due to delayed gastric emptying.
4. Start Slowly to Avoid Nausea
If taking multiple new supplements makes you nauseous, start with just the multivitamin for a week, then add B12, then add others gradually. Always take supplements with food, not on an empty stomach.
5. Stay Consistent
Set a daily alarm or use a pill organizer. Nutrient deficiencies develop gradually—by the time you feel symptoms, you're already severely deficient. Prevention through consistent supplementation is key.
Sample Daily Supplement Schedule:
Frequently Asked Questions
Do I really need to take vitamins on semaglutide?
Yes. When you reduce food intake by 30-50%, you're getting proportionally fewer vitamins and minerals—even if you're eating perfectly healthy foods. Supplementation isn't optional; it's essential for preventing deficiencies, maintaining muscle mass, and supporting long-term health during treatment.
Can I just eat healthier instead of taking supplements?
In theory yes, but in practice it's extremely difficult. If you're only eating 1,000-1,400 calories per day and dealing with food aversions and reduced appetite, getting 100% of your nutritional needs from food alone is nearly impossible. Supplements provide insurance against deficiencies.
Will vitamins interfere with semaglutide's effectiveness?
No. Vitamins and minerals do not interfere with how semaglutide works. In fact, adequate nutrition supports better weight loss outcomes by maintaining energy levels, muscle mass, and overall health. Deficiencies can actually slow weight loss progress.
Can supplements make my nausea worse?
They can if taken on an empty stomach or in large doses all at once. Always take supplements with food, start with smaller doses, and add new supplements gradually. If a particular supplement makes you nauseous, try a different form (gummies vs pills, liquid vs capsules) or take it later in the day when nausea typically improves.
Should I get blood work to check my vitamin levels?
Yes, ideally. Ask your healthcare provider to check vitamin B12, vitamin D (25-hydroxyvitamin D), iron/ferritin, and a complete metabolic panel at baseline and every 6-12 months while on semaglutide. This allows you to adjust supplementation based on your actual needs rather than guessing.
Can I take bariatric vitamins designed for weight loss surgery?
Yes, bariatric multivitamins (designed for gastric bypass/sleeve patients) are excellent options for semaglutide users. They're formulated for people with reduced food intake and absorption issues, making them ideal for GLP-1 medication users. Brands like BariMelts, Celebrate, and ProCare Health are good options.
How much does vitamin supplementation cost per month?
A complete supplement regimen (high-quality multivitamin, B12, vitamin D, protein powder, calcium/magnesium) typically costs $40-80 per month—far less than the cost of treating nutritional deficiencies. High-quality supplements are worth the investment for long-term health.
Start Your Semaglutide Journey with CoreAge RX
CoreAge RX is our #1 recommended provider for semaglutide—offering compounded medication at $99/month with complete medical support, nutritional guidance, and free shipping.
See our affiliate disclosure for information about our financial relationships with reviewed companies.
The Bottom Line
Vitamin and mineral supplementation is not optional when taking semaglutide—it's an essential part of safe, effective treatment. Dramatically reduced food intake means dramatically reduced nutrient intake, even if your diet quality is excellent.
At minimum, every semaglutide user should take a high-quality multivitamin, vitamin B12, vitamin D3+K2, and focus on adequate protein intake (through food or supplementation). Calcium, magnesium, iron (if deficient), and omega-3s provide additional support for bone health, muscle preservation, and overall wellness.
The cost of supplements ($40-80/month) is minimal compared to the cost of treating nutritional deficiencies, muscle loss, or bone density problems down the line. Invest in your health now by prioritizing proper nutrition and supplementation throughout your semaglutide journey.
Work with your healthcare provider to test nutrient levels periodically and adjust your supplement regimen as needed. Your long-term health depends on maintaining adequate nutrition during treatment—don't leave it to chance.